Light source module, optical device, and method for producing light source module

ABSTRACT

A light source module including a phosphor wheel having a phosphor layer to emit fluorescence when excited with light emitted from a light source; and a drive section disposed on a phosphor-layer side of the phosphor wheel, the drive section configured to rotate the phosphor wheel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. application Ser. No.16/424,520, filed May 29, 2019, which is based on and claims prioritypursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No.2018-120208, filed on Jun. 25, 2018, in the Japan Patent Office, theentire disclosure of which is incorporated by reference herein.

BACKGROUND Technical Field

Embodiments of this disclosure relate to a light source module, anoptical device, and a method for producing a light source module.

Description of the Related Art

A technique of irradiating a phosphor layer laid on a rotatable phosphorwheel with excitation light to use emitted fluorescence in a lightsource module used in an image projection apparatus (so-calledprojector) or the like that projects an image on a screen or the like tomagnify the display is known.

As such a light source module, a technique of providing the phosphorlayer in a recess formed on a surface of the phosphor wheel so as toreduce diffused light, which becomes stray light, among the lightemitted from the phosphor layer and make effective use of the lightemitted from the phosphor layer.

SUMMARY

In one aspect of this disclosure, there is provided an improved lightsource module including a phosphor wheel having a phosphor layer to emitfluorescence when excited with light emitted from a light source; and adrive section disposed on a phosphor-layer side of the phosphor wheel,the drive section configured to rotate the phosphor wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned and other aspects, features, and advantages of thepresent disclosure would be better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings, wherein:

FIG. 1 is a view illustrating an example of a configuration of alighting device according to an embodiment of the present disclosure;

FIG. 2 is an enlarged plan view illustrating an example of a phosphorwheel according to the embodiment of the present disclosure;

FIG. 3 is an enlarged plan view illustrating an example of a color wheelaccording to the embodiment of the present disclosure;

FIG. 4A and FIG. 4B are views, each of which illustrates an example ofarrangement of a drive section according to the embodiment of thepresent disclosure;

FIG. 5A and FIG. 5B are views, each of which illustrates an example of aconfiguration of a light shielding unit according to the embodiment ofthe present disclosure;

FIG. 6 is a view schematically illustrating a situation wherefluorescence spreads hemispherically around a light emitting pointaccording to the embodiment of the present disclosure;

FIG. 7A and FIG. 7B are views, each of which illustrates an example of aconfiguration in which a lens barrel, a side plate, and a holderaccording to the embodiment of the present disclosure are integrated;

FIG. 8 is a flow diagram illustrating an example of a method forproducing a light source module according to the embodiment of thepresent disclosure;

FIG. 9 is a view illustrating an example of a lens group and the lensbarrel according to the embodiment of the present disclosure; and

FIG. 10 is a view illustrating an example of a configuration of a lightsource module according to a second embodiment of the presentdisclosure.

The accompanying drawings are intended to depict embodiments of thepresent disclosure and should not be interpreted to limit the scopethereof. The accompanying drawings are not to be considered as drawn toscale unless explicitly noted.

DETAILED DESCRIPTION OF EMBODIMENTS

In describing embodiments illustrated in the drawings, specificterminology is employed for the sake of clarity. However, the disclosureof this patent specification is not intended to be limited to thespecific terminology so selected and it is to be understood that eachspecific element includes all technical equivalents that operate in asimilar manner and achieve similar results.

Although the embodiments are described with technical limitations withreference to the attached drawings, such description is not intended tolimit the scope of the disclosure and all of the components or elementsdescribed in the embodiments of this disclosure are not necessarilyindispensable.

Referring now to the drawings, embodiments of the present disclosure aredescribed below. In the drawings for explaining the followingembodiments, the same reference codes are allocated to elements (membersor components) having the same function or shape and redundantdescriptions thereof are omitted below.

A description will hereinafter be made on embodiments of the presentdisclosure with reference to the drawings. In the drawings, the samecomponents may be denoted by the same reference codes and theoverlapping description may not be made.

In each of the embodiments, a lighting device provided with a lightsource module will be described as an example. Here, the lighting deviceis a device that irradiates an image generation unit such as a digitalmicromirror device (DMD) for generating a projection image with light inan image projection apparatus such as a projector. Such a lightingdevice is an example of the “optical device” described in the claims.

FIG. 1 is a view illustrating an example of a configuration of alighting device according to a first embodiment of the presentdisclosure. As illustrated in FIG. 1, a lighting device 100 includes alight source 101, a fly eye lens 102, a lens 103, a lens 104, awavelength selective polarization separation element 105, and a quarterwave plate 106. The lighting device 100 also includes a lens group 107,a lens barrel 108, a side plate 109, a holder 110, a phosphor wheel 111,a drive section 112, a lens 113, a color wheel 114, and a light tunnel115.

In FIG. 1, a light source module includes the phosphor wheel 111, thedrive section 112, the lens group 107, and a light shielding unit. Thelight shielding unit includes the side plate 109 and the drive section112. A detailed description will separately be made on the lightshielding unit with reference to FIG. 5 to FIG. 6.

Although not illustrated in FIG. 1, the light source module furtherincludes a casing that accommodates (houses) the phosphor wheel 111, thedrive section 112, the lens group 107, and the light shielding unit.Such a light source module is an example of the “light source module”described in the claims.

In the lighting device 100, the light source 101 emits light having alinear polarization component. In the present embodiment, as an example,the following description will be made on a case where the light source101 is a laser diode array in which multiple laser diodes are arrangedin parallel and each of the multiple laser diodes emits a blue laserbeam with a wavelength λB having a P polarization component (which is Pwave). The wavelength λB can satisfy 400 nm<λB<470 nm, for example.

However, the light source 101 is not limited to the above. As the lightsource 101, one of the single laser diode that emits blue light, a lightemitting diode, and an organic electro luminescence (EL) element may beused, or a light source in which at least some of these are combined maybe used. Alternatively, the laser diode, the light emitting diode, theorganic EL element, or the like that emits light having a wavelengthrange of an ultraviolet region may be used, or a light source in whichat least some of these are combined may be used.

The blue laser beam emitted from the light source 101 is used asexcitation light that generates fluorescence in the phosphor wheel 111.

The fly eye lens 102 is an optical element in which multiple lenses arearranged vertically and horizontally in a matrix in a form of fly eyes.With the fly eye lens 102, for example, an area irradiated with thelight emitted from the light source 101 can have uniform illuminancedistribution.

The blue laser beam emitted from the light source 101 is incident, assubstantially parallel light beam, on the wavelength selectivepolarization separation element 105 via the fly eye lens 102, the lens103, and the lens 104. The wavelength selective polarization separationelement 105 is an optical path switching unit having a predeterminedspectral transmittance characteristic.

The wavelength selective polarization separation element 105 has acharacteristic of reflecting the P wave and not reflecting S wave(transmitting the S wave) at the wavelength λB of the light source 101.The light having a wavelength of approximately 500 nm or greater passesthrough the wavelength selective polarization separation element 105regardless of whether the light is the P wave or the S wave (regardlessof a polarization characteristic). As the wavelength selectivepolarization separation element 105, a polarization beam splitter can beused, for example.

The blue laser beam of the P wave, which is incident on the wavelengthselective polarization separation element 105, is reflected by thewavelength selective polarization separation element 105 and is guidedto the quarter wave plate 106 that is a polarization converter formutually converting linearly polarized light and circularly polarizedlight. The light transmitted through the quarter wave plate 106 ischanged from the P wave (P polarized light) to the circularly polarizedlight, and is incident on the phosphor wheel 111 via the lens group 107.

The polarization converter is not limited to the quarter wave plate. Forexample, a polarization converter in which an oblique vapor-depositedfilm of Ta 2O5 (tantalum pentoxide) or the like is formed on an incidentsurface of any lens forming the lens group 107, or the like may be used.Here, the oblique vapor-deposited film is a film in which a vapordeposition target is placed obliquely with respect to a fly direction ofa vapor deposition material (a direction toward a vapor depositionsource) and in which the vapor deposition material is obliquelydeposited with respect to a normal to a predetermined surface of thevapor deposition target.

The lens group 107 can be configured by appropriately combining abiconvex lens, a plano-convex lens, and the like, for example. The lensgroup 107 has: a function of focusing the substantially parallel lightbeam in a spot shape on the phosphor wheel 111; and a function of usingthe focused light as the excitation light to parallelize divergent lightemitted from the phosphor layer of the phosphor wheel 111 and convertthe divergent light into the substantially parallel light beam. Byexpanding a numerical aperture (NA) of the lens group 107, it ispossible to condense more of the divergent light, which is emitted fromthe phosphor layer and spreads hemispherically, and to improvecondensing efficiency. The lens group 107 is an example of the “opticalsystem” described in the claims.

The lens group 107 is accommodated in the lens barrel 108 and is pressedby an annular plate spring member. The annular plate spring member isfixedly attached to the lens barrel 108 by a screw or the like. In thisway, the lens group 107 is fixedly mounted onto the lens barrel 108. Bymeans of the annular plate spring member, the lens group 107 can befixedly mounted onto the lens barrel 108 without being scratched. Thelens barrel 108 is an example of the “lens barrel” described in theclaims.

Here, FIG. 2 is an enlarged plan view illustrating an example of thephosphor wheel used in the embodiment, and is a view of the phosphorwheel as viewed from an incident light side. As illustrated in FIG. 2,the phosphor wheel 111 is configured that a disk-like member, that is, arotating body is divided into multiple fan-like regions (segments), eachof which emits the different fluorescence. The phosphor wheel 111 isrotationally driven in a circumferential direction such that the regionirradiated with the light from the wavelength selective polarizationseparation element 105 changes sequentially.

More specifically, in the circumferential direction, the phosphor wheel111 is divided into the three fan-like regions (segments) including: ayellow (Y) phosphor region 1111 formed with a yellow (Y) phosphoremitting yellow fluorescence; a green (G) phosphor region 1112 formedwith a green (G) phosphor emitting green fluorescence; and a reflectingsurface region 1113 formed with a reflecting surface for reflecting theincident light.

The yellow (Y) phosphor region 1111 uses the blue laser beam as theexcitation light to generate the yellow fluorescence having a longerwavelength than the blue laser beam. The green (G) phosphor region 1112uses the blue laser beam as the excitation light to generate the greenfluorescence having a longer wavelength than the blue laser beam. Thereflecting surface region 1113 reflects the incident blue laser beam asthe blue light as is.

The phosphor wheel 111 rotates to switch the segment arranged at anincident position of the light from the lens group 107, so as to be ableto extract reflected light of each of the yellow fluorescence, the greenfluorescence, and the blue laser beam. The above description is made onthe example in which the reflecting surface region 1113 is used for aregion where the blue light is extracted. However, the region where theblue light is extracted is not limited to the reflecting surface region1113. For example, the blue light may be extracted by using at least oneof a transparent region, a region with a hole, a diffusion region, andthe like.

The transparent region is transparent glass, for example, and transmitsthe blue laser beam. The blue laser beam passes through the region withthe hole as is. In an incident direction of light from the lens group107, a reflecting surface is provided at a point ahead of thetransparent region where the blue laser beam that has been transmittedor has passed, and the light transmitted through the transparent regionor the light passing through the region with the hole reflected byreflecting surface. In this way, the blue light can be extracted. In thediffusion region, the blue laser beam is diffusely reflected. Forexample, the diffusion region can have a structure in which a largenumber of uneven structures in different sizes are formed on a surface.

In addition, the example in which the yellow phosphor region and thegreen phosphor region are used as the phosphor regions is described.However, one of the yellow phosphor region and the green phosphor regionmay be used. Alternatively, a phosphor region in a different color mayreplace the existing phosphor region and/or may be providedadditionally.

Furthermore, in addition to the blue laser, a light source such as a redlaser diode may additionally be provided as the light source.

Referring back to FIG. 1, the drive section 112 such as a stepping motorfor rotating the phosphor wheel 111 is coupled to an axis of thephosphor wheel 111. The holder 110 holds the drive section 112 and thephosphor wheel 111 coupled to the drive section 112.

The phosphor wheel 111 rotates at predetermined timing as a result ofdriving of the drive section 112. In this way, the incident position ofthe light from the lens group 107 is switched to any of the threesegments of the yellow (Y) phosphor region 1111, the green (G) phosphorregion 1112, and the reflecting surface region 1113. A portion 111 a ofthe phosphor layer illustrated in FIG. 1 is irradiated with the lightfrom the lens group 107 and generates the fluorescence. The fluorescenceemitted from the phosphor layer is light emitted from a uniformdiffusion surface, luminance of which is not changed in any direction,and is so-called Lambertian light distribution light.

Each of the yellow fluorescence and the green fluorescence respectivelyemitted from the yellow (Y) phosphor region 1111 and the green (G)phosphor region 1112 passes through the lens group 107 and the quarterwave plate 106 in a reverse direction from the incident light, and isincident on the wavelength selective polarization separation element105. Each of the yellow fluorescence and the green fluorescence at thetime is in a state of random polarization.

As described above, the wavelength selective polarization separationelement 105 transmits the light having the wavelength of approximately500 nm or greater regardless of the polarization characteristic. Thus,the yellow fluorescence and the green fluorescence, which are generatedby the phosphor wheel 111, pass through the wavelength selectivepolarization separation element 105 and is incident on the color wheel114 through the lens 113.

Meanwhile, the light reflected by the reflecting surface region 1113 ofthe phosphor wheel 111 passes through the lens group 107 and the quarterwave plate 106 in the reverse direction of the incident light. Here, thecircularly polarized light, which is incident on the reflecting surfaceregion 1113, is maintained as the circularly polarized light after thereflection, but becomes the circularly polarized light that rotates inan opposite direction from the incident light due to the reflection. Forexample, the circularly polarized light that rotates clockwise at thetime of the incidence becomes the circularly polarized light thatrotates counterclockwise after the reflection. Then, after passingthrough the quarter wave plate 106, the circularly polarized lightbecomes the linearly polarized light, a polarization direction of whichis orthogonal to a polarization direction of the incident light.Consequently, the linearly polarized light passes through the wavelengthselective polarization separation element 105 and is incident on thecolor wheel 114 through the lens 113.

FIG. 3 is an enlarged plan view illustrating an example of the colorwheel used in the embodiment, and is a view of the color wheel as viewedfrom the incident light side. As illustrated in FIG. 3, the color wheel114 is configured that a disk-like member, that is, a rotating body isdivided into multiple fan-like regions (segments). More specifically, inthe circumferential direction, the color wheel 114 is divided into thefour fan-like regions (segments) including a red (R) region 1141, agreen (G) region 1142, a transparent region 1143, and a diffusion region1144.

In the color wheel 114, the red (R) region 1141 is a region where adichroic filter for transmitting red light is formed, transmits thelight in a wavelength range of approximately 600 nm or greater, andreflects the light in the other wavelength ranges. The green (G) region1142 is a region where a dichroic filter for transmitting green light isformed, transmits the light in a wavelength range from approximately 500nm to approximately 580 nm, and reflects the light in the otherwavelength ranges.

The transparent region 1143 transmits the light in all the wavelengthranges as is. The transparent region 1143 may be the transparent glassor the like, or may be configured to have a hole. The diffusion region1144 diffuses and transmits the light in all the wavelength ranges. Forexample, the diffusion region 1144 can have the structure in which thelarge number of the uneven structures in the different sizes are formedon a surface.

The color wheel 114 rotates to switch the segment arranged at anincident position of the light from the lens 113, so as to be able toextract the red light, the green light, the yellow light, and the bluelight.

Here, as a region that extracts the light without changing thewavelength, a reflecting surface region may be used. In addition, theexample of the regions where the dichroic filters transmitting the redlight and the green light are formed is described. However, the regionis not limited thereto. In the region, any one of the dichroic filtersmay be formed. Alternatively, a dichroic filter in a different color mayreplace the existing dichroic filter and/or may be formed additionally.Furthermore, in addition to the blue laser, the light source such as thered laser diode may additionally be provided as the light source.

Referring back to FIG. 1, although not illustrated, a drive section suchas a stepping motor for rotating the color wheel 114 is provided on anaxis of the color wheel 114. The color wheel 114 rotates atpredetermined timing as a result of driving of the drive section. Inthis way, the incident position of the light from the lens 113 isswitched to any of the four segments of the red (R) region 1141, thegreen (G) region 1142, the transparent region 1143, and the diffusionregion 1144. That is, on optical paths of the blue laser beam and thefluorescence, any of the segments is alternately arranged in time.

The blue light is incident on the color wheel 114 at the timing when thediffusion region 1144 is arranged at the incident position of the lightfrom the lens 113. The blue light is diffused when passing through thediffusion region 1144. As a result, coherence of the blue light, thatis, the laser beam is lost, and unevenness and a speckle that appears ona screen or the like are reduced. The light that has passed through thediffusion region 1144 becomes blue irradiation light.

The yellow fluorescence is incident on the color wheel 114 at the timingwhen one of the transparent region 1143 and the red (R) region 1141 isarranged at the incident position of the light from the lens 113. At thetiming when the transparent region 1143 is arranged, yellow light withmaximum brightness is obtained. The light that has passed through thetransparent region 1143 becomes yellow irradiation light. At the timingwhen the red (R) region 1141 is arranged, red light is obtained. Thelight that has passed through the red (R) region 1141 becomes redirradiation light.

The green fluorescence is incident on the color wheel 114 at the timingwhen the green (G) region 1142 is arranged at the incident position ofthe light from the lens 113. In this way, purity of green is adjusted,and the light that has passed through the green (G) region 1142 becomesgreen irradiation light.

The light that has passed through each of the regions in the color wheel114 is incident on the light tunnel 115.

The light tunnel 115 is a cylindrical hollow member. Each of theirradiation light incident on the light tunnel 115 is repeatedlyreflected inside the light tunnel 115. Consequently, illuminancedistribution of each of the irradiation light becomes uniform at an exitof the light tunnel 115. That is, the light tunnel 115 has a function asan illuminance uniformizing unit that reduces unevenness of lightintensity of each of the irradiation light. Note that, instead of thelight tunnel 115, another illuminance uniformizing unit such as the flyeye lens may be adopted.

The image generation unit such as the DMD is irradiated with the light,the illuminance distribution of which is uniformized through the lighttunnel 115.

The lighting device 100 can irradiate the image generation unit with thelight as described above. The image generation unit can generate theprojection image using the irradiated light.

Here, a description will be made on the arrangement of the drive sectionin the light source module according to the present disclosure withreference to FIG. 4A and FIG. 4B.

FIG. 4A is a view illustrating an example of arrangement of the drivesection 112 in a light source module 200 according to the embodiment ofthe present disclosure. In FIG. 4A, the drive section 112 is arranged ona surface side where a phosphor layer 111 b (hatched portion) of thephosphor wheel 111 is provided. When the light source module 200, inwhich the drive section 112 is arranged just as described, isaccommodated in a casing 201, a distance from a surface of the casing201 opposing the phosphor wheel 111 to the phosphor wheel 111 becomes alength indicated by an arrow 202 a in FIG. 4A.

FIG. 4B is a view illustrating an example of the arrangement of thedrive section 112 in a light source module 300 as a comparative exampleof the embodiment of the present disclosure. In FIG. 4B, componentshaving the same functions as those of the light source module 200 of theembodiment are denoted by the same reference codes.

In FIG. 4B, the drive section 112 is arranged on a surface of thephosphor wheel 111 on an opposite side to the surface provided with thephosphor layer 111 b (hatched portion). When the light source module300, in which the drive section 112 is arranged just as described, isaccommodated in the casing 201, the distance from the surface of thecasing 201 opposing the phosphor wheel 111 to the phosphor wheel 111becomes a length indicated by an arrow 202 b in FIG. 4B. As apparentfrom the drawing, the length of the arrow 202 a is less than the lengthof the arrow 202 b.

In the present embodiment, the drive section 112 is arranged on thesurface side of the phosphor wheel 111 where the phosphor layer 111 b isprovided. In this way, the distance from the surface of the casing 201opposing the phosphor wheel 111 to the phosphor wheel 111 is reduced.Thus, a length of the light source module in a Z-direction can bereduced, and the light source module can be downsized.

Next, a description will be made on the light shielding unit in thelight source module according to the embodiment of the presentdisclosure with reference to FIG. 5A and FIG. 5B.

FIG. 5A and FIG. 5B are side views of the lighting device 100illustrated in FIG. 1. FIG. 5A is a side view of the lighting device 100illustrated in FIG. 1 as viewed from a positive X-direction, and FIG. 5Bis a side view of the lighting device 100 illustrated in FIG. 1 asviewed from a negative X-direction.

As illustrated in FIG. 5A and FIG. 5B, the lens group 107 isaccommodated in and fixed mounted onto the lens barrel 108. The sideplate 109 is arranged on the phosphor layer of the phosphor wheel 111 ina manner to close a portion of the phosphor layer, which is irradiatedwith the light from the lens group 107 and emits the fluorescence, inthe positive X-direction. Electrical wiring 112 a is coupled to thedrive section 112.

Here, the fluorescence emitted from the phosphor layer of the phosphorwheel 111 is the divergent light that spreads hemispherically around thelight emitting point in the reverse direction from the incidentdirection of the excitation light. Of such divergent light, the lightthat propagates in a direction beyond the NA of the lens group 107 isnot fully collected by the lens group 107. Thus, there is a case wherethe emitted fluorescence partly deviates from the effective aperture ofthe lens group 107, becomes the stray light, and cause noise such asflare in the projection image.

FIG. 6 is a view schematically illustrating a situation where thefluorescence spreads hemispherically around the light emitting point. InFIG. 6, the phosphor layer 111 b of the phosphor wheel 111 is irradiatedwith the excitation light from the lens group 107 in an arrow directionin the drawing. From a portion 111 a of the phosphor layer 111 b onwhich the excitation light is incident, the fluorescence is emitted, anddivergent light 111 c spreads hemispherically and propagates. Of thedivergent light 111 c, light 107 a included in the NA of the lens group107 is collected by the lens group 107 and used as the irradiationlight. Meanwhile, the light that propagates in the direction beyond theNA of the lens group 107 (hatched light of the divergent light 111 c)deviates from the effective aperture of the lens group 107 and becomesthe stray light as described above.

Referring back to FIG. 5A and FIG. 5B, in the present embodiment, theside plate 109 is arranged in the manner to close the portion, whichemits the fluorescence, in the positive X-direction. Accordingly, of theemitted fluorescence, the light that propagates in the positiveX-direction and becomes the stray light is shielded, so as to preventgeneration of the noise such as the flare in the projection image.

A surface of the side plate 109 is subjected to antireflection treatmentto prevent the fluorescence incident on the surface from being reflectedand becoming the stray light. For example, the antireflection treatmentis treatment of dying the surface of the side plate 109 matte black orroughening the surface to scatter the incident light on the surface. Ofthe surface included in the side plate 109, at least the regionirradiated with the fluorescence may be subjected to the antireflectiontreatment of the side plate 109.

Meanwhile, the drive section 112 is arranged on the phosphor layer ofthe phosphor wheel 111 in a manner to close the portion of the phosphorlayer, which is irradiated with the light from the lens group 107 andemits the fluorescence, in the negative X-direction. In this way, of theemitted fluorescence, the light that propagates in the negativeX-direction and becomes the stray light is shielded, so as to preventthe generation of the noise such as the flare in the projection image.

A surface of the drive section 112 is subjected to the antireflectiontreatment to prevent the fluorescence incident on the surface from beingreflected and becoming the stray light. For example, the antireflectiontreatment of the drive section 112 is treatment of dying the surface ofthe drive section 112 the matte black or roughening the surface toscatter the incident light on the surface. Of the surface included inthe drive section 112, at least a portion irradiated with thefluorescence may be subjected to the antireflection treatment.

As described above, in the present embodiment, each of the side plate109 and the drive section 112 has the function of the light shieldingunit and prevents the stray light generated by the fluorescence.

Note that the configuration including the side plate 109 and the drivesection 112 is an example of the “light shielding unit that is providedaround a portion emitting the fluorescence and at least partiallyshields the emitted fluorescence” described in the claims.

Next, a description will be made on a configuration in which the lensbarrel, the side plate, and the holder in the embodiment of the presentdisclosure are integrated with reference to FIG. 7A and FIG. 7B. FIG. 7Ais a perspective view of the phosphor wheel 111 illustrated in FIG. 1 asviewed in a positive Z-direction and from the positive X-direction. FIG.7B is a perspective view of the phosphor wheel 111 illustrated in FIG. 1similarly as viewed in the positive Z-direction and from the positiveX-direction.

As described above, the side plate 109 is arranged in the manner toclose the portion, which emits the fluorescence, in the positiveX-direction. As an example, the side plate 109 has a shape of a partialcylinder as illustrated. Due to the arrangement of the side plate 109,of the emitted fluorescence, the light that propagates in the positiveX-direction and becomes the stray light is shielded. In addition, thedrive section 112 is arranged in the manner to close the portion, whichemits the fluorescence, in the negative X-direction. Accordingly, of theemitted fluorescence, the light that propagates in the negativeX-direction and becomes the stray light is shielded.

As illustrated in FIG. 7A and FIG. 7B, the lens barrel 108, the sideplate 109, and the holder 110 of the drive section 112 are combined asingle unit. Such a member is formed by cutting a metal material such asaluminum or iron, for example. Alternatively, such a member may beformed by using a die to mold plastic. In the case of plastic molding,cost reduction and processing time reduction can be achieved in massproduction. However, in the case where the phosphor wheel 111 generatesexcessively high heat due to the irradiation of the excitation light,the members may melt. Thus, heat-resistant plastic is desirably used. Inthe case where the member in which the lens barrel 108, the side plate109, and the holder 110 are integrated is formed of the metal material,there is no concern that the phosphor wheel 111 melts by generation ofthe heat and thus becomes the heat resistant member.

As described above, as the NA of the lens group 107 is expanded, thecondensing efficiency of the fluorescence by the lens group 107 isimproved. However, in the case where a distance between the lens group107 and the phosphor wheel 111 fluctuates due to an installation errorof the lens group 107, the condensing efficiency may be reducedsignificantly. The reduced condensing efficiency causes reducedbrightness of the projection image in the image projection apparatus orthe like. On the other hand, in the case where it is attempted tosuppress the reduced condensing efficiency by such a distancefluctuation, high-precision assembly adjustment is required. As aresult, an assembly time and assembly cost will be increased.

According to the present embodiment, the lens barrel 108, the side plate109, and the holder 110 are combined as a single unit. Thus, thedistance between the lens group 107 and the phosphor wheel 111 can becontrolled in accordance with processing accuracy of the members. As aresult, it is possible to suppress the reduced fluorescence condensingefficiency, which is associated with the fluctuation in the distancebetween the lens group 107 and the phosphor wheel 111, withoutincreasing the assembly time and the assembly cost. In addition, sincethe fluctuation in the distance between the lens group 107 and thephosphor wheel 111 can be suppressed, the lens group 107 having thelarge NA, which can be brought closer to the phosphor wheel 111, can bedesigned and adopted. Therefore, and the fluorescence condensingefficiency is improved, and the bright lighting device can be realized.

FIG. 8 is a flow diagram illustrating an example of a method forproducing the light source module according to the embodiment of thepresent disclosure. In the method for producing illustrated in FIG. 8,as illustrated in FIG. 9, it is assumed that a lens group having atwo-lens configuration including a first lens 91 and a second lens 94 isaccommodated in and mounted onto the lens barrel 108. In addition, thelens barrel 108, the side plate 109, and the holder 110 are the singleintegrated member. In FIG. 9, the lens barrel 108 as a portion of such amember is illustrated while the rest of the member is not illustrated.

In FIG. 8, first, the first lens 91 is arranged at a predeterminedposition in the lens barrel 108 (step S801).

Next, the first lens 91 is held in a negative Z-direction by a platespring member 92, and the plate spring member 92 is attached to the lensbarrel 108 by a screw 93, so as to mount the first lens 91 onto the lensbarrel 108 (step S803).

Next, the second lens 94 is arranged at a predetermined position in thelens barrel 108 (step S805).

Next, the second lens 94 is held in the negative Z-direction by a platespring member 95, and the plate spring member 95 is fixedly attached tothe lens barrel 108 by a screw 96, so as to mount the second lens 94onto the lens barrel 108 (step S807).

Next, the drive section 112 is fixedly attached to the holder 110 (stepS809).

Next, the member, in which the lens barrel 108, the side plate 109, andthe holder 110 are integrated, is fixedly attached to the casing 201(step S811). Such attachment may be performed with an adhesive orperformed by fitting or screwing.

In this way, the light source module 200 of the present embodiment canbe manufactured.

As it is described so far, according to the present embodiment, thedrive section that rotates the phosphor wheel is provided on the surfaceside of the phosphor wheel where the phosphor layer is provided, and thedrive section forms at least the part of the light shielding unit. Thus,the length of the light source module in the incident direction of theexcitation light can be reduced, and the light source module can bedownsized. In addition, of the fluorescence emitted from the phosphorlayer, the light that becomes the stray light can be shielded due toprovision of the light shielding unit. Thus, the noise such as the flarein the projection image can be prevented.

According to the present embodiment, at least one of the drive sectionand at least the part of the surface of the side plate is subjected tothe antireflection treatment. Thus, it is possible to suppress the straylight, which is generated by the reflected light on the drive section orthe surface of the side plate, and to prevent the noise such as theflare in the projection image.

In the present embodiment, the description is made on the example inwhich the member in which the lens barrel 108, the side plate 109, andthe holder 110 are integrated is used. However, the present disclosureis not limited to the above. For example, it may be configured that thelens barrel 108 is separated from the side plate 109 and the holder 110.In such a case, when the lens barrel 108 is fixed to one of the sideplate 109 and the holder 110, the lens barrel 108 may be fixed via avibration-proof member such as vibration-proof rubber or vibration-proofgel. Because the vibration-proof member absorbs vibrations associatedwith the rotation of the drive section 112, it is possible to preventthe lens group 107, which is accommodated in the lens barrel 108, frombeing displaced due to the vibrations and to prevent the reducedfluorescence condensing efficiency caused by the displacement of thelens group 107.

The holder 110 in the present embodiment may hold the drive section 112via a high heat conductive member having higher heat conductivity thanthe holder 110. More specifically, a heat conductive sheet that is madeof a silicone resin, ceramic, or the like is interposed between theholder 110 and the drive section 112, and the drive section 112 is fixedto the holder 110. Alternatively, grease with the high heat conductivitymay be used as the high heat conductive member, and the grease with thehigh heat conductivity may be interposed between the holder 110 and thedrive section 112.

The drive section 112 may generate heat by the rotation. Due to the heatgeneration of the drive section 112, a temperature of the phosphor layer111 b in the phosphor wheel 111 may be increased, and fluorescenceluminous efficiency may be reduced. When the heat generated by the drivesection 112 is transferred to the holder 110 side by the heat conductivesheet, heat transfer to the phosphor wheel 111 can be suppressed, andthe reduced fluorescence luminous efficiency of the phosphor layer 111b, which is caused by the heat generation of the drive section 112, canbe suppressed.

Second Embodiment

Next, a description will be made on a light source module according to asecond embodiment of the present disclosure. The description of the samecomponents that are already described in the first embodiment may not bemade.

When the phosphor layer of the phosphor wheel is irradiated with theexcitation light, the portion irradiated with the excitation light inthe phosphor layer generates the heat. When the phosphor layer isbrought into a high temperature state due to the heat generation, thefluorescence luminous efficiency of the phosphor layer may be reduced.In the present embodiment, the light source module includes a heatdissipating member. The heat is exchanged between the phosphor layer andthe heat dissipating member, and the heat dissipating member dissipatesthe heat. In this way, the phosphor layer can be cooled.

FIG. 10 is a view illustrating an example of a configuration of thelight source module according to the present embodiment. A light sourcemodule 200 a has a heat sink 210. A through hole is provided on asurface of a casing 201 that opposes the phosphor wheel 111. The heatsink 210 is arranged adjacent to a surface of the phosphor wheel 111 onan opposite side to the surface provided with the phosphor layer 111 bthrough the through hole, and is fixedly attached to the casing 201. Theheat sink 210 is an example of the “heat dissipating member” describedin the claims.

Because the heat sink 210 is arranged in no contact with the phosphorwheel 111, the rotation of the phosphor wheel 111 is not inhibited bythe heat sink 210. As the heat sink 210 is arranged close to thephosphor wheel 111, cooling efficiency of the heat sink 210 isincreased. Thus, the heat sink 210 is desirably arranged as close aspossible to the phosphor wheel 111.

In the present embodiment, the heat sink is described as the example ofthe heat dissipating member. However, a heat pipe may be used for heatexchange between the phosphor layer and one of gas and a liquid as amedium.

In addition, in the present embodiment, the description is made on theexample in which the heat sink 210 and the casing 201 are configuredseparately. However, the heat sink 210 and the casing 201 may beintegrated. That is, a portion of the casing 201 that is adjacent to thephosphor wheel 111 may be provided with a structure of increasing asurface area of a fin or the like, and such a fin or the like mayfunction as the heat dissipating member. In such a case, the casing 201is desirably formed of a material having the high heat conductivity suchas aluminum.

The other effects are the same as those described in the firstembodiment.

The description is made so far on the examples of the embodiments of thepresent disclosure. However, the present disclosure is not limited tosuch specific embodiments, and various modifications and changes can bemade within the scope of the gist of the present disclosure as set forthin the claims.

For example, in the embodiments, the description is made on the lightsource module that irradiates the phosphor layer with the excitationlight and uses the fluorescence emitted in the opposite direction fromthe incident direction of the excitation light. However, the presentdisclosure is not limited to the above.

For example, the present disclosure may be applied to a light sourcemodule that irradiates the phosphor layer with the excitation light anduses the fluorescence emitted in the same direction as the incidentdirection of the excitation light.

Numerous additional modifications and variations are possible in lightof the above teachings. It is therefore to be understood that, withinthe scope of the above teachings, the present disclosure may bepracticed otherwise than as specifically described herein. With someembodiments having thus been described, it will be obvious that the samemay be varied in many ways. Such variations are not to be regarded as adeparture from the scope of the present disclosure and appended claims,and all such modifications are intended to be included within the scopeof the present disclosure and appended claims.

1. A light source module comprising: a phosphor wheel having a phosphorlayer to emit fluorescence when excited with light emitted from a lightsource; a drive section disposed on a phosphor-layer side of thephosphor wheel, the drive section configured to rotate the phosphorwheel.
 2. The light source module according to claim 1, furthercomprising: a light shielding unit disposed around a portion of thephosphor layer that emits fluorescence, to shield a least a part of theemitted fluorescence; a side plate disposed around the portion of thephosphor layer, the side plate being at least a part of the lightshielding unit to shield the at least of a part of the emittedfluorescence; a holder configured to hold the drive section; and a lensbarrel configured to accommodate an optical system, wherein at least twoof the side plate, the holder, and the lens barrel are combined as asingle unit.
 3. The light source module according to claim 1, whereinthe phosphor layer is configured to emit light when irradiated withexcitation light emitted from the light source, and the phosphor layeris configured to be irradiated with the excitation light from adrive-section-side surface of the phosphor wheel.
 4. The light sourcemodule according to claim 2, wherein at least a part of the lightshielding unit includes a surface subjected to antireflection treatmentto prevent reflection of the fluorescence.
 5. The light source moduleaccording to claim 2, further comprising a casing configured to housethe drive section, the optical system, and the light shielding unit, atleast a part of the casing including a surface subjected toantireflection treatment to prevent reflection of the fluorescence. 6.The light source module according to claim 1, further comprising: a heatdissipating member disposed adjacent to a surface of the phosphor wheelon an opposite side to the surface provided with the phosphor layer, andconfigured to dissipate heat generated in the portion emitting thefluorescence.
 7. The light source module according to claim 6, wherein acasing and the heat dissipating member are combined as a single unit. 8.The light source module according to claim 2, wherein the lens barrel isa member separated from the light shielding unit and the holder, and thelens barrel is attached to at least one of the light shielding unit andthe holder with a vibration-proof member to absorb vibrations.
 9. Thelight source module according to claim 2, wherein the holder isconfigured to hold the drive section with a high heat conductive memberhaving higher heat conductivity than the holder, disposed between theholder and the drive section.
 10. An optical device comprising: thelight source module according to claim
 1. 11. A method of producing alight source module including a phosphor wheel having a phosphor layerto emit fluorescence, the method comprising: housing an optical systemthat focuses the fluorescence emitted from the phosphor layer of thephosphor wheel, within a lens barrel included in a single unit of a sideplate, a holder holding a drive section, and the lens barrel, the sideplate disposed in an area of the phosphor layer that emits fluorescenceto shield at least a part of the emitted fluorescence, the drive sectiondisposed on a phosphor-layer side of the phosphor wheel and connectedwith the phosphor wheel to rotate the phosphor wheel, attaching theoptical system housed in the lens barrel to the lens barrel with avibration-proof member to absorb vibrations; attaching the drive sectionto the holder; and attaching the single unit to a casing that houses thedrive section, the optical system, and the single unit.